Synthetic oil base lubricating grease compositions



United States Patent SYNTHETIC OIL BASE LUBRICATING GREASE COMPOSITIONS ing Compan a corporation of Delaware No Drawing. Application May 16, 1952, Serial No. 288,301

6 Claims. (Cl. 252--42) This invention relates to lubricating compositions having outstanding lubricating properties at both high and low temperatures. Particularly the invention relates to synthetic lubricating compositions which are the formals of branched chain alcohols.

In an effort to obtain superior lubricating compositions having specific and unusual characteristics there have been developed new synthetic lubricating compositions. One class of materials which have been found to be especially operable as synthetic lubricants are the long chain aliphatic esters, both the simple dibasic acid esters and the complex esters prepared from dibasic acids, glycols, and alcohols. In general these synthetic lubricating oils are characterized by viscosity properties that are outstanding both at low and high temperature when compared to mineral lubricating oils. These outstanding high and low temperature properties are especially desirable for the lubrication of combustion engines which are designed to operate at high and low temperatures. It has been found that mineral lubricating oils are unsatisfactory for lubricating these combustion engines because of their somewhat restricted operating temperature range due to the limits of their viscosity characteristics.

The present invention contemplates the formation of a new type of synthetic lubricant which has outstanding viscosity properties and is thereby useful as a substitute for mineral lubricating compositions. They are particularly desirable for automotive use or for use in other type combustion engines operating under widely diversified conditions of temperature.

These new synthetic lubricants are, so far as is known, new compositions of matter, and comprise the acetals made from branched chain aliphatic alcohols and formaldehyde or a polymer of formaldehyde. Other aldehydes, such as acetaldehyde, may be used, however, formaldehyde is preferred.

The synthetic lubricants of this invention have the following general formula: (RO)2CH2 wherein R is a branched chain aliphatic radical having from 8 to 20 carbon atoms.

These formals are very simply prepared in accordance with the following technique.

Formaldehyde in aqueous solution mers of formaldehyde, such as paraformaldehyde, is refiuxed with the desired branched chain alcohol. Acidic materials such as hydrochloric acid, sulfuric acid, sulfamic acid, p-toluenesulfonic acid, sodium acid sulfate, or any strong acid may be used as a catalyst. Entraining liquids such as hexane, heptane fractions, benzene and the like may be used in order to remove the water of reaction, although good yields are readily obtainable without a water entrainer. The product may be water washed followed by an alkali wash and dried over some suitable drying agent, such as anhydrous potassium carbonate, or by distillation using a hydrocarbon as a water entrainer. Distillation may be under reduced pressure if desired.

It is essential that the aliphatic alcohol portion of the or any of the polyr 2,746,924 C ?atented May 22, 1956 formal radical be highly branched in order to satisfy the viscosity requirements for lubricating oil use. Various straight chain formals have been prepared but those of proper chain length have pour points that are too high for ordinary lubrication work. The formal of n-tetradecyl alcohol melts at 107 F. (Chem. Abs. 42, 4922 (1948)), and that of n-nonadecyl alcohol melts at F. (Ber. 72B, 1060 (1939)). The formal of technical C16 alcohol, a straight chain alcohol, was prepared and was a solid at room temperature. A formal of technical lauryl alcohol was a liquid at room temperature but had an ASTM pour point of 65 F., making it entirely unsatisfactory as a lubricating oil at low temperatures.

Particularly desirable branched chain alcohols are those highly branched chain aliphatic alcohols prepared by the 0x0 synthesis. This Oxo synthesis may be described as being the catalytic reaction product of an olefin with carbon monoxide and hydrogen. The reaction occurs at temperatures in the order of 300-400 F., at pressures in the range of about 1000 to 3000p. s. i. In the presence of a suitable catalyst, ordinarily a heavy metal carbonyl such as cobalt carbonyl, there is formed an aldehyde which is subsequently hydrogenated to a primary alcohol. This process was first developed in Germany and is described in U. S. Patent No. 2,327,066, is sued to Roelen in 1943.

In general the oxygenated group in a product from an olefin by the OX0 process is thought of as becoming attached to an unsaturated carbon which holds at least one hydrogen atom. In those cases where the carbon monoxide attacks a saturated carbon atom it must be assumed either that that carbon has become unsaturated prior to reaction by a shift of a hydrogen atom or that the attack is directly on a carbon atom that is truly saturated. For example, 2-butene has been reported to give 1-pentanol and Z-methylbutanol in equal quantities, a result that cannot be explained on the simple basis that oxonation takes place only on unsaturated carbons holding hydrogen. 2,3-di1nethyl-2-butene also reacts giving only 3,4-dimethyl-l-pentanol; in this olefin no hydrogen is attached to the unsaturated carbon atoms and the attack of carbon monoxide must either be on a rearranged olefin or on a saturated carbon atom.

It has been found that particularly desirable alcohols for the formation of the formals of this invention can be prepared by the application of the 0x0 synthesis to polymers and copolymers of C3 and C4 monoolefins. These monoolefins are readily available in refinery streams and processes for their conversion to liquid copolymers have been worked out by the art. One such process, known as U. 0. P. polymerization, consists of passing the olefin-containing stream in liquid phase in contact with an acid catalyst comprising phosphoric acid impregnated on kieselguhr. Other acidic catalysts, such as phosphoric acid or copper phosphate impregnated on silica gel, sulfuric acid, Friedel-Crafts catalysts, activated clays, silica-alumina, copper pyrophosphate, etc., may be used. Suitable conditions when employing phosphoric acid catalysts of the U. 0. P. type are temperatures of 300 to 500 F., pressures from 250 to 5,000 p. s. i. and feed stocks comprising refinery streams containing propylene and mixed butylenes. Suitable feed stocks, for example, may contain from 15 to 60 mol percent propylenes, from 0.5 to 15 mol percent butylenes, and from 0.1 to 10 mol percent isobutylene, the remaining being saturated hydrocarbons. Other suitable feed stocks are the dimer and trimer of isobutylene.

The preferred 0x0 alcohols employed in forming the formals of this invention are those having from 8 to 20 carbon atoms derived from olefin copolymers hav- Structure of Cr x0 alcohols Prepared from (ls-Ct It will be noted that Oxo alcohols derived from the olefins produced by C3C4 polymerization are mostly methyl substituted and there is relatively little or no substitution on the second carbon atom.

In order to more explicitly define the instant invention several highly branched chain formals were prepared by the procedure described above. The alcohols used to prepare the formals were the highly branched chain Oxo alcohols prepared by the interaction of carbon monoxide and hydrogen with an olefin and contained the carbon chain length shown. with a highly refined Mid-Continent distillate mineral lubricating oil and two of the outstanding synthetic lubricating oils known to the art. The viscosity and flash point data of these materials are set out in Table I below.

These lubricants were compared It will be seen that the Oxo formals of the instant invention compare very favorably with the best synthetic lubricant the art has thus far been able to develop. It is also to be seen that these materials possess viscosity characteristics that make them much more advantageous than mineral oils under conditions of varying temperatures.

A further comparison of mineral lubricating oil and the formals of this invention was made by the Lauson 25-hour engine test at 300 F. using a standard fuel. The engine was examined before and after the test and the merit ratings are given according to the test Standards. Comparative data on this test using a formal of C13 Oxo alcohol and a highly refined mineral lubricating oil of 60 S. S. U at 210 F. and a viscosity index of 68 are set out below.

TABLE II Lauson engine test [26 Hours at 300 F.]

1 Rating scale 1 to 10, 1 being a perfect rating.

It is to be noted that the Lauson engine test data reported in Table II above point out that the varnish demerit rating for the formal of this invention is considerably better than that of the high quality lubricating oil and that the bearing weight loss of 0.05 gram per bearing is as good as that experienced with the mineral oil. This indicates an overall advantage for the use of the synthetic lubricant of this invention. It is also within the concept of this invention to prepare lubricating compositions by blending the formals of this invention with various other synthetic lubricants, for instance, blends of the formals of highly branched chain alcohols containing from 8 to 20 carbon atoms with dibasic acid esters such as esters of adipic, sebacic, glutaric and succinic acid, with complex ester type synthetic lubricants such as alcohol-dibasic acid-glycol-dibasic acid-alcohol esters, alcohol-dibasic acid-glycol-monobasic acid esters, etc. form lubricating compositions that have many desirable properties.

It has also been found that lubricating compositions prepared by thickening the formals of this invention, or blends of these formals with other synthetic lubricants, with a grease forming soap have desirable properties which make them especially advantageous for the lubri- TABLE I Comparative data for mineral oil and synthetic lubricants Mineral Synthetic Synthetic Formal of Formal 0! Formal of Lubricatin Lubricant. Lubricant Ora 0x0 C13 0x0 G1! 0x0 011 A 13 Alcohol Alcohol Alcoh Kinematic Viscosity (Us. at):

Solid 3, 900 3, 430 693 7, 788

--65 Solid Solid 26,000 99,860 Flash Point 445 425 450 345 419 440 Pour Point (F.)-- -25 -65 75 75 -7n 1 di-2-ethylhexyl sebacste +35% of a reaction product of tetraethylene glycol and the half ester of ndlple acid with Hthylhexannl.

I 010 0x0 alcohol diester c! adiple acid.

cation of moving metal parts where a liquid cannot be used. These grease compositions are simply and economically prepared using as a thickening agent any of the common grease forming soaps. The alkali or alkaline earth metal soaps of high molecular weight substantially saturated fatty acids are used and the grease compositions prepared by any of the methods with which the art is familiar. For instance, soaps such as the oleates, stearates or ricinoleates of sodium, potassium, lithium, calcium, barium, strontium, aluminum, iron, zinc, copper and the like may be used as thickeners for the formals of the invention as Well as soaps formed by heating animal, fish or vegetable oils with soda, lime, baria hydrate or lithia hydrate. Examples of some of these grease compositions are set out below.

EXAMPLE I Formulation:

7.5 lithium stearate 7.5 lithium hydroxy stearate 0.5% phenothiazine 84.5% formal of C Oxo alcohol Preparati0n.The combined soaps were dispersed cold in the formal and then heated While stirring to 400 F. At this temperature the inhibitor (phenothiazine) was added and the mass poured into a shallow pan for cooling. When cold the grease was homogenized to a soft uniform consistency.

Properties:

Appearance Light cream color,

smooth, buttery. Penetrations, 77 F., mm./ 10:

7.5 lithium stearate 7.5 lithium hydroxy stearte 0.5% phenothiazine 84.5 formal of C13 0x0 alcohol Preparation.Same as Example I.

Properties:

Appearance Light cream color,

smooth, buttery.

Penetrations, 77 F., mm./l0:

Unworked 275. Worked (60 strokes) 295. Worked (100,000 strokes) 340. Dropping point F.) 365. Water solubility Nil (boiling water). Norma Hoffman oxidation (hours to 3 p. s. i. drop in oxygen pressure) 200.

EXAMPLE r11 Formulation:

7.5% lithium stearate 7.5 lithium hydroxy stearate 20.0% formal of C10 Oxo alcohol 64.0% complex ester (adipic acid-Ca Oxo alcohol-1-3 butanediol) 1.0% phenyl-alpha-naphthylamine Preparati0n.The combined soaps were mixed with the formal and heated to 350 F. At this temperature the soap began to swell and disperse in the formal. The complex ester was then slowly added while continuing to stir and heat and the mass heated to 400 F. until all the soap was in solution. Phenyl-alpha-naphthylamine was added and the grease cooled in shallow pans.

Properties:

Appearance Light brown, slightly rough texture, short fiber.

Penetrations, 77 F., mm./l0:

Unworked 280. Worked (60 strokes) 285. Worked (100,000 strokes).. 340.

Dropping point F.) 370.

Norma Hoffman oxidation (hours to 5 p. s. i. drop in oxygen pressure) 332.

To reiterate briefly, the instant invention is directed toward new and improved synthetic lubricating compositions which comprise formals of the formula: (RO)2CH2, wherein R is a highly branched aliphatic carbon chain having from 8 to 20 carbon atoms. In the preferred embodiment the formals are prepared by reacting with formaldehyde the alcohols obtained by the interaction of an olefin with carbon monoxide and hydrogen in the 0x0 process.

What is claimed is:

l. A lubricating composition which comprises a formal of the formula: (RO)2CH2, wherein R is a highly branched chain aliphatic radical corresponding to that of an alcohol having from 8 to 20 carbon atoms made by the interaction of an olefin with carbon monoxide and hydrogen in the Oxo process containing combined therein a grease forming amount of a metal soap.

2. A lubricating composition which comprises a formal of a Gil-C20 alcohol made by the interaction of an olefin with carbon monoxide and hydrogen in the 0x0 process, thickened to a grease consistency with the alkali metal soap of a high molecular Weight fatty acid.

3. A lubricating composition which consists essentially of a formal of a C16 highly branched chain alcohol, thickened to a grease consistency with an alkali metal soap of a high molecular weight saturated fatty acid.

4. A lubricating composition which consists essentially of a formal of a C13 highly branched chain alcohol, thiciened to a grease consistency with an alkali metal soap of a high molecular weight saturated fatty acid.

5. A lubricating composition which consists essentially of a formal of a C10 highly branched chain alcohol, thickened to a grease consistency with an alkali metal soap of a high molecular Weight fatty acid.

6. A lubricating grease composition which consists essentially of a blend of a formal of a Cs-C2u highly branched chain alcohol with a complex ester which has been prepared by formin the Z-ethyl-hexanol half ester of adipic acid and reacting two moles of said half ester with one mole of tetraethylene glycol, said blend being thickened to a grease consistency with the alkali metal soap of a high molecular weight fatty acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,331,367 Baggett Oct. 12, 1943 2,382,874 Gresham Aug. 14, 1945 2,388,409 Harvey Nov. 6, 1945 2,497,133 Morway et a1. Feb. 14, 1950 2,512,771 Glavis et a1. June 27, 1950 2,639,266 Dilworth et a1 May 19, 1953 

1. A LUBRICATING COMPOSITION WHICH COMPRISES A FORMAL OF THE FORMULA: (RO)2CH2, WHEREIN R IS A HIGHLY BRANCHED CHAIN ALIPHATIC RADICAL CORRESPONDING TO THAT OF AN ALCOHOL HAVING FROM 8 TO 20 CARBON ATOMS MADE BY THE INTERACTION OF AN OLEFIN WITH CARBON MONOXIDE AND HYDROGEN IN THE OXO PROCESS CONTAINING COMBINED THEREIN A GREASE FORMING AMOUNT OF A METAL SOAP. 